4b: Use formulas and strategies, such as decomposition, to compute the perimeter

and area of triangles, parallelograms, trapezoids, the circumference and area of circles, and find the area of more complex

shapes. (DOK 2)

By: Deia Sanders

PerimeterThe Perimeter of a polygon is the distance around it.

Because a square and a rectangle are special types of polygons, they have a special perimeter formula. The

triangle and any other unknown-sided polygon will use the “sum of all the sides” as the formula.

Square = 4s (s is the length of the side)Rectangle = 2(l + w) (l is the length and w is the width)

All other polygons = add the sides

Let’s Review

Examples on Page

66

Homework:

Handout #1 Page 93

Day 2

Area of

Polygons

!!!

Area of Polygons

Triangle: A = ½ bh

Parallelogram: A = bh

Square: A = s2

Rectangle: A = lw

Let’s work

examples

on pages 67-69

Homework

Handout #2 Page 95

Day 3

Area of

Trapezoids!

!!

Area of Trapezoid

Trapezoid: 1/2h(b1 + b2)

Let’s work

examples on

pages 69-72!!

Homework

Handout #3 Page 97

Day 4

Circumferen

ce and Area

of Circles!!!

Circumference of a Circle

Circumference: C = pi(d)

Circumference is the distance around a

circle

Let’s look at page 73!

Area of a Circle

The area of a circle is the region or space inside the circle. The measurement will be measured in square units.

Let’s look at page 73!

Homework

Handout #4

Page 99

Day 5

Irregular

Polygons!!!

Irregularly Shaped Polygons

Step 1. Break down the original figure into more basic shapes, such as squares, rectangles, triangles, or circles.

Step 2. Find the area of the basic shapes using the formulas.

Step 3. Combine the areas of the basic shapes so that the area of the irregularly shaped polygon can be determined.

Lets look at

pages 74

and 75!!!

Homework

Handout #5Page 101